If it is Komui or Johnny (or some other non-exorcist) it would mean that they haven't located the Heart yet, which is still feasible. I really hope it's not Lenalee.

Are the Bookmen human? What special abilities do they posses other than the obvious memory ones? What's the deal with Lavi's eyepatch (does he wear it as part of his observance training? Is he hiding something under there?).

And Kanda. I assume he was some child they picked up off the street and experimented on, but he is Japanese, yes? Isn't Japan overrun with high level akuma? More explanation please!